Cyrill of Jerusalem confirms what was in the incipit of the Earliest Gospel, since he agrees perfectly with the Marcionite version of the descent to Sheol.
19. Death was struck with dismay on beholding a new visitant descend into Hades, not bound by the chains of that place. Why, O porters of Hades, were you scared at sight of Him? What was the unwonted fear that possessed you? Death fled, and his flight betrayed his cowardice. The holy prophets ran unto Him, and Moses the Lawgiver, and Abraham, and Isaac, and Jacob; David also, and Samuel, and Esaias, and John the Baptist, who bore witness when he asked, Are You He that should come, or look we for another Matthew 11:3? All the Just were ransomed, whom death had swallowed; for it behooved the King whom they had proclaimed, to become the redeemer of His noble heralds. Then each of the Just said, O death, where is your victory? O grave, where is your sting ? For the Conqueror has redeemed us.
http://www.newadvent.org/fathers/310114.htm
Hence, when the John Baptist was in
prison and said the famous question:
Are You He that should come, or look we for another?
...he was
not in an earthly prison at all: he was in
Sheol.
Luke and Matthew are particularly false when they report that the question and answer episode happened on the earth. In particular, what sounds more false than anything is the quote of Isaiah in the answer of Jesus.
Marcion tells us what happened after that dramatic question:
“In addition to his blasphemy against God Himself, he advanced this also, truly speaking as with the mouth of the devil, and saying all things in direct opposition to the truth—that Cain, and those like him, and the Sodomites, and the Egyptians, and others like them, and, in fine, all the nations who walked in all sorts of abomination, were saved by the Lord, on His descending into Hades, and on their running unto Him, and that they welcomed Him into their kingdom.”
But the serpent which was in Marcion declared that Abel, and Enoch, and Noah, and those other righteous men who sprang from the patriarch Abraham, with all the prophets, and those who were pleasing to God, did not partake in salvation. For since these men, he says, knew that their God was constantly tempting them, so now they suspected that He was tempting them, and did not run to Jesus, or believe His announcement: and for this reason he declared that their souls remained in Hades.
(Irenaeus, From Book I, chap. 27,
Against Heresies)
Hence, John the Baptist is made an evil character, in the Earliest Gospel.